Stock market breadth held up well in Monday morning trading, but a selloff among stocks linked to the artificial-intelligence trade was weighing on the S&P 500. The S&P 500 was down 1.7%, even though 324 of its members were on the rise.

U.S. technology shares dropped sharply on Monday as surging interest in Chinese startup DeepSeek's low-cost artificial intelligence model raised doubts about the sector's lofty valuations. The tumble in global equities prompted a widespread flight to safety,